Increasingly, devices designed to enable the consumption of video content feature a large persistent store; and support both broadcast and networking technologies.
An operator wishing to make video content available to devices equipped with multiple reception capabilities has a number of transmission methods and technologies to choose from, including unicast (via a managed network or via the Internet), broadcast (via satellite, terrestrial or cable systems) or multicast (via a managed network).
Broadcast capability will generally involve leasing transponders for an agreed period. Unicast delivery via the Internet can be provisioned in a variety of ways, including deploying content servers in a suitable facility, making use of media hosting services, making content available via a pay-as-you-go ‘cloud’ service or enlisting the services of a regional or global content delivery network (CDN). Internet Protocol television (IPTV) multicast or video on demand (VOD) capability may exist if the provider is able to make use of a managed IP network, for example if delivering content to the customers of a single internet service provider (ISP).
Each of these mechanisms can be used to deliver content at varying rates and times relative to viewing. For example, content could be delivered by broadcast transmission over a period before viewing time (as is typically the case with broadcast push delivery), or could be delivered by unicast transmission at a higher rate commencing at viewing time (as is typically the case with progressive download).
Each approach incurs cost in different ways. For example, satellite transponders are normally leased for long periods for relatively large sums, typically millions of Euros annually, whereas a typical Internet based CDN charges for the delivery of video content on the basis of quantity delivered, typically a few cents per gigabyte (GB). Meanwhile, wholesale bandwidth purchased at a co-location facility is charged on the basis of peak utilization, typically tens of Euros per megabit per second (Mb/s).
The cost of delivery also depends on the nature of the delivery method. For example, content broadcast by satellite can be acquired by any tuner within its geographical footprint, typically a large area that may include millions of delivery destinations. By contrast, delivery from a CDN by unicast transmission requires a distinct copy of the content to be sent to each destination, causing delivery cost to increase proportionally with the number of viewers.
Each potential path between delivery source and destination has associated capacity bounding the content that can be delivered within a given time frame. For example, in the case of broadcast this capacity is determined by both the available transponder bandwidth and the number and type of tuners available at the destination. In the case of Internet or IPTV delivery this capacity is determined partly by broadband access connectivity but may also depend on one or more points of shared capacity between source and destination, for example an ISP's connectivity with the wider Internet.
Internet delivery resources are often provisioned by capacity on the basis of expected peak utilization. However, demands on capacity over time are rarely constant and thus resources are often underutilized during off-peak periods. Online video services such as the iPlayer (available from the British Broadcasting Corporation (BBC), United Kingdom) have been shown to exhibit a usage profile with a relatively high peak-to-mean ratio, similar to that of broadcast television viewing. Therefore, there is a relatively high likelihood of such capacity being used inefficiently for this type of service.
Each delivery to be made may be associated with business criteria such as delivery deadlines, priorities or cost targets.
CDN overlay networks are a technology focused on Internet delivery mechanisms, typically combining multiple CDNs and a peer-to-peer (P2P) capability of some kind (see http://blogs.gartner.com/lydia_leong/2008/10/21/cdn-overlays-and-more-on-mediamelon)
Minimizing the weighted sum of objective functions is a well known technique from the field of multiple objective optimization and used in situations where other types of optimization are computationally infeasible.
The following references are believed to represent the state of the art:    European Patent Application EP 1 476 992 to Mitsubishi Denki Kabushiki Kaisha;    United States Patent Application US 2008/0025222 to Nikolova et al.;    United Kingdom Patent Application GB 2 418 267 to QinetiQ Ltd.;    United States Patent Application US 2009/100459 to Riedl et al.;    European Patent EP 1 563 669 to Nokia Corporation;    International Patent Application WO2009/087550 to Alcatel Lucent;    U.S. Pat. No. 7,423,973 to Qualcomm, Inc.;    International Patent Application WO2006/072825 to Nortel Networks Limited; and    International Patent Application WO2009/076121 to Cisco Technology, Inc.